Regulation of Body Metabolism Flashcards
What are the energy inputs into the body and what are the outputs?
Inputs (diet) :
- hunger
- satiey
- social
- psychological
outputs:
- heat (~ 50%)
- work
> transport, mechanical and chemical
What are some examples of work done in the body?
- transport:
> across memebranes, between compartments - mechanical
> movement -> muscle contractions, secretion - Chemical:
> synthesis -> growth and maintenance
> storage -> chemical bonds -> ATP, Glyogen, fat
what types of heat energy are lost from the body?
> unregulated:
- energy released from chemical reactions
- metabolism and muscle contractions
- lost to environment
body temperature increases with exercise and after meal
thermoregulation
- cutaneous vasodilation and sweating - heat loss
- thermogenesis -> shivering, piloerection - heat gain
What does the body store energy in?
> ATP - short term energy
glycogen
- glucose polymer
- more compact form of energy for storage
- liver (100g) and skeletal muscle (200g)
triglycerides
- adipose tissue (20kg)
- efficient storage - holds more energy per gram
- but, energy harder to access and metabolism slower
how does shivering help maintain weight balance?
> mechanism to prevent lowering of core body temp
acute exposure to mild coldness = increased energy expenditure
low exposure to season coldness = lower physiological thermogenesis
describe leptin in context of weight loss?
> for weight loss you need sustained energy intake to be less than energy expenditure
fat produced leptin (peptide hormone)
- increases in body fat = increase in leptin, hypothalamus senses this and reduces appetite
- obese people may be resistant to the affects of leptin.
Describe the glucose nutrient pool
> carbohyrates are ingested -> goes to the glucose nutrient pool > immediately used as energy ATP > brain metabolism > excess is : - stored as glycogen (liver and muscle) - stored as triglycerides (fat)
Describe the triglyceride nutrient pool
> fats are ingested -> triglyceride pool
most stored as fat in adipose tissue
some immediate energy use
Describe the Amino acid nutrient pool
> protein ingested
amino acid nutrient pool
used for body’s protein synthesis
excess:
- converted to glycogen and stored in the liver
- converted to fat and stored in adipose tissue
describe the differences in the fed vs fasted state
fed:
- absorption - up to 4hrs post meal
- anabolic > catabolic
- energy used or stored
fasted:
- post absorption - from 4hrs post meal
- catabolic > anabolic
- energy released for work
describe the different types of fat
> fat stores (white fat)
- subcutaneous fat
- visceral/intra-abdominal fat
- joints - eg knee, palms and soles
> Brown fat
- increase in metabolic activity: can generate heat
- non-shivering thermogenesis
- increased in lean individuals and increased during cold adaptation
What are some factors affecting dietary and energy intake?
- food availability
- money
- habits
- time
- social and psychological influences
- role of hunger
- metabolic changes - pathological problems
- pleasure of eating
- stimulus of good food
- macronutrient content
> regulated by the hypothalamus
- hunger centre
- satiety centre
what is metabolic rate and what are the different kinds?
= energy expenditure > resting metabolic rate: - to sustain resting metabolism for one day - kcal/day - general metabolism for everyday > basal metabolic rate: - clinical definition for metabolism - measured under standardised conditions - minimum rate to functions and stay alive by lying down and not moving etc - kcal/hr/m2 body surface - BMR
What is the breakdown of metabolic energy expenditure in the body?
> basal metabolic rate =60%
thermic effect of food = 10%
muscular activity = 30%
what are some factors affecting metabolic rate?
> age and gender
- male> female, decrease in BMR with age
amount of lean muscle
- muscle = higher O2 consumption than adipose, even at rest
activity level:
- physical activity and muscle contraction increase MR (>BMR)
diet
- diet induced thermogenesis (protein >CHO»>Fat)
hormones
- thyroid hormones and catechoilamines increase BMR
genetics
- inherited traits - metabolic efficiency
pathophysiology
- inflammation, trauma, fever
